From: Philippe Ayral (payral@club-internet.fr)
Date: 05/19/01-01:44:44 AM Z
Thanks for all your answers. The Pot. Ox. was the culprit. I tried an another one, lab quality, and it dissolved completely even at room temperature. (300g/l).
"alnovo@inwind.it" wrote:
> > I dissolved 300g of Potassium Oxalate in 1000 ml of demineralized hot
> > water (the one in supermarket).
> > Everything was OK and the solution absolutely transparent but this
> > morning, when I wanted to store the bottle, all the stuff is
> > crystallized at the bottom of the bottle.
> >
> > Philippe
>
> Pot.ox. monohydrate has a solubility of nearly 30% (30 g in 100 g of total <solute+solvent> solution). If you pour off the solution, can you weight the crystals and determine how much did not dissolve at 20°C?
> Are you sure it is really pot.ox? If you have some potassium permanganate at hand, you can perform a simple (but not definitive) qualitative analysis.
> Adds ome drops of pot.perm. to a warm and acidifyed solution (with sulphuric acid) of pot.ox. The pink colour should disappear after some tenths of seconds (this reaction is faster when more permanganate have reacted).
>
> Alberto
-- Ayral Philippe 52, rue de Vallard 74240 Gaillard France Tél/Fax: +33 (0)450 39 79 81 http://www.focale.ch
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